A transport network (also known as a provider network) may be used to connect multiple geographically dispersed access networks (also known as customer networks) via a wide area network. An access network (AN) is a network, which connects an access device of a host to a core switching device. One example technology for carrying user traffic through a transport network is Transparent Interconnection of Lots of Links (TRILL), which is a Layer 2 (L2) network standard recommended by Internet Engineering Task Force (IETF). TRILL is configured to solve deficiencies of Spanning Tree Protocol (STP) in a large-scale data center. In a TRILL network, a device running a TRILL protocol may be referred to as a Routing Bridge (RB) device. The RB device may transmit a Hello packet periodically, so as to discover and maintain a neighbor relationship with a neighbor RB. Another example is Ethernet Virtual Interconnect (EVI) where a site network may access a public network via an edge device (ED).